Patent GB-535485-A (GB)
Title: Improvements in or relating to machines for finishing the surface of a workpiece by abrasion
IPC: B24B27/00
Filed: 1939-12-13
Abstract: 535,485. Centreless grinding. CINCINNATI GRINDERS, Inc. Dec. 13, 1939, No. 32174. Convention date, July 31. [Class 60] In a machine for finishing the surface of a workpiece, such as a poppet valve stem, tappet, piston pin, or antifriction roller, by abrasion a work regulating member and an abrading member are arranged to engage opposite sides of the work and means are provided for imparting relative rotation and superimposed rotary oscillating movements to the members and also for causing the abrading member to vibrate transversely with respect to the work regulating member. A machine for continuous operation on a number of work pieces consists of a work table 24 rotated about a fixed part 23 by a motor through belt 34, spur gear 38, 39, bevel gear 43, 44, worm gear 46 and shaft 48 carrying a pinion 49 engaging a gear wheel 50 carried by the table. The table is provided with a number of radially adjustable slides 56 on which are trunnioned at 58 brackets 59 held by springs 60 in contact with adjustable stops 62 and normally pulled back by handles 61 when the work 20 is to be inserted. Each bracket carries a blank 63 from which extend blade springs 64, 65, which vibratingly support a flanged plate 66 to which is adjustably secured a roller 69 and which is provided with springs 82 for pressing a block 73 against the flange. The block is notched at 74 to receive the trunnions 78 of a tool holder 76, which carries a grooved abrading element. The block 73 is carried by a blade spring 72 mounted on a block 70, and the trunnions 78 are retained in position by spring pressed pins 80. The work 20 is pressed by the springs 82 between the abrading element and a work regulating wheel 31, the end of the work engaging the tip 85 of a support 86 extending from the bracket 59. The rollers 69 engage an annular cam plate 28 which co-operates with the table 24 but driven at a greater speed by gear 42, 41 from the shaft 40. The cam is provided with undulations of different heights and engages the rollers 69 so as to vibrate the tools vertically. An adjustable stop 88 limits the movement of the roller 69 in the direction of the cam. The regulating wheel is given a rotary oscillation by an eccentric portion 52, Fig. 4, of the shaft 36 engaging a portion 53 pivoted to an arm 32 on the shaft 30. Each particle of the abrasive thus operates in a path forming an advancing helix, Fig. 15, so as to prevent the formation of hills and valleys in the work. The bed 22 may be provided at the loading position with a projecting portion having inclined ends 90, 91, Fig. 3, engaging lugs 92 on rock arms 93 on the tool slides so as through a finger, plunger, and lugs to rock the member 59 automatically on trunnions 97 into and out of work-engaging position. In a modification, the springs 64, 65 are dispensed with, the member 66 being slidably mounted in anti-friction guides in a channel-shaped bracket 59, and the roller 69 being held in contact with the cam 28 by a coiled spring. The lubricating oil may be supplied to the tools through a passage 108 in the part 23 co-operating with an annular passage 111 in the table connected by a pipe 112 with a distributing ring 113 communicating by flexible tubes 115 with the groove in the abrading tool. The lubricant is collected in the drain flange 25 and returned to a chamber in the bed where it is filtered and recirculated by a pump.